Description:Engineering / Aerospace manufacturing
Abstract:Unmanned Aerial Vehicles (UAVs) are increasingly being used for surveillance, telecommunications, reconnaissance operations, and precision delivery missions in the modern combat theatre. Future concepts of UAVs such as the Joint Unmanned Combat Air System (J-UCAS) and sensor craft are paradigm breakers, since they are being conceived as flexible, mobile high-altitude alternatives to space-based platforms such as satellites. The new UAV concepts have opened the doors to many exciting opportunities for modeling as well as for carrying out innovative and nontraditional designs. The aerodynamic behavior of these aircraft, which is not quite well understood yet, can have a significant influence on the considered UAVs’ performance. In this regard, it is necessary to enhance and calibrate existing numerical tools and develop new numerical tools for predicting complex aerodynamic behavior with a high level of accuracy. The development of AeroVANT, a comprehensive computational tool for the aerodynamic analysis of unconventional high aspect ratio joined-wing UAVs, is aimed in this direction. AeroVANT can serve as a robust, accurate, and reliable prediction tool for coming up with future UAV concepts and designs that involve structures with high flexibility and high aspect-ratio. n this effort, it is envisaged that the aerodynamic model will need to predict the unsteady nonlinear loads on streamlined UAVs with high aspect-ratio wings and high flexibility executing arbitrary subsonic maneuvers. To accomplish this task, the general unsteady nonlinear three-dimensional vortex-lattice method (UVLM) that has been undergoing development off and on at Virginia Tech for more than two decades has been used. The UVLM that is used for the computation of aerodynamic loads is a cost-efficient approach to study fluid-structure interactions in complex lifting surfaces like a full-scale UAV. The solutions are evaluated in the time domain and they are not restricted to small periodic motions. This approach allows nonlinear and unsteady aerodynamic effects to be included in the model. AeroVANT can accommodate more than one body; thus, steady and unsteady aerodynamic interference can be modeled with accurate estimates of the phasing among loads. It can run time accurately and can account for the changing circulation distribution on the lifting surfaces, the time dependent velocity potential, and the motion of the free wakes (free wake relaxation). The AeroVANT code follows a highly modular approach and was written in Fortran 90. Such implementations make the code more readable, maintainable, portable and extensible.